This project proposes to continue the long term objective of studying the temporal bone and central nervous system histopathologic changes in specific and general disorders due to overt or possible cochlear and/or vestibular abnormalities. Correlation will be sought between the histopathologic findings in human temporal bones and central nervous system with the patients history, results of auditory and vestibular studies and therapy. Hearing acuity of hospitalized patients will be monitored by the use of conventional audiologic, vestibular and other electrophysiologic tests except in the fetus and newborn. Temporal bones and brains from these evaluated patients will be removed at the time of autopsy and processed for light microscopic examination. The cochlear and vestibular sensory cells and the first order neurons innervating these structures will be quantitatively evaluated. Similarly, a quantitative study of the cell population in the primary auditory nuclei will be performed. There are only scattered studies which provide correlatable values of vestibular and auditory function with histopathologic changes of the temporal bone and membranous labyrinth; and almost none which address changes in the central nervous system. This study provides the opportunity for these correlations and will lead to a better understanding of disorders of hearing and balance and possible to more adequate clinical preventive and therapeutic measures.